Many so-called child-proof or, more properly, child-resistant closures have been proposed for use on various types on containers in which medicines, household chemicals and the like are sold in retail markets. Most of those previously suggested closures have comprised either a one-piece cap which cooperates with a specially configured bottle neck finish or a two-piece cap consisting of two nested inverted cup shaped elements, both of which are special and both of which have parts especially designed for cooperation with each other.
The purpose of all of these child-resistant closures is to make it significantly difficult for a small child, say, up to the age of six, or so, to gain access to the material in the container while yet making it possible for an older child or an adult who can comprehend the necessary manipulations to open the particular container.
Most of these previously suggested child-resistant closures are quite expensive to manufacture, requiring more material, more complex and expensive molds and, sometimes, difficult assembly problems, which increase the costs of their manufacture.
Very few of the previously suggested child-resistant closures make use of what is well known in the trade as a "standard" threaded metal screw cap. Such a "standard" threaded metal screw cap almost always has a circumferentially extending series of ribs or serrations formed in the upper edge of its threaded skirt at what might be called the "shoulder" of the cap i.e., where the skirt joins the flat top. These ribs or serrations are provided in order to enable one who wishes to turn the cap to hold it tightly i.e., they are friction creating elements.
It is the principal object of the instant invention to provide a child-resistant overcap which is specifically designed so that it is adapted to be merely snapped over a standard metal screw cap of the type described above and, after being snapped in place, renders the two-part closure effectively child-resistant.
It is another, more specific object of the instant invention to provide a child-resistant overcap for use with a standard threaded metal screw cap which readily can be varied to increase or decrease the degree of resistance to its actuation, depending upon the serious nature of the material in the container and the degree of child-resistance which it is desired to provide.
It is yet a further object of the instant invention to provide a single-piece, child-resistant overcap which, in itself, is not a closure for a bottle or other container having a threaded neck but which quickly and readily can be snapped into place over a standard metal screw cap regardless of the material from which the bottle itself is fabricated and without requiring any special cooperating elements on the bottle or its neck and without requiring any special design of the metal screw cap itself.
While the over-cap of the invention will be illustrated as applied to a metal screw cap, it is also contemplated that the over-cap readily can be used with screw caps fabricated from hard plastic materials, the only requirement being the presence thereon of the vertical ribs or serrations similar to those normally present on metal screw caps.